南水北调来水对密云水库水质及水生生物的影响

Influence of water from South-to-North Water Transfer on water quality and aquatic organisms of Miyun Reservoir

2015年9月11日,南水北调水正式进入密云水库,源水区丹江口水库水与密云水库水进行水质汇兑,由于两种水源水质化学特征存在差异,汇兑之后,密云水库水生态存在重构风险。因此,南水入库后,进行汇水区及整个库区的水质、水生态调查监测,明确水库水环境变化,对指导密云水库水质安全管理调度具有重要意义。通过南水入库对密云水库水质、浮游藻类、大型水生植物影响的分析,可以看出:南水入库调水初期,密云水库各水质指标(除pH外)均有所升高;pH呈先下降再升高的趋势,最低达8.2,到2020年恢复到南水入库前水平;2015-2020年密云水库各监测富营养化状态指数值在36~43之间,均为中营养水平,富营养化状态呈逐年改善趋势。库东、金沟浅水区域发生水华的概率大于深水区域;南水入库前后,密云水库浮游植物种类数量变化不大,但优势藻种构成季节变化显著;南水入库后,库区岸边带的沉水植物、挺水植物以及陆生草本植物全部被淹没致死,目前发现潮河入库口和白河入库口存在大量的水生植物,库北岸边带有狐尾藻、大茨藻零星分布。预计库岸带水生植物的大面积恢复还需要多年时间。

On September 11, 2015, the water of the south-to-North Water Diversion project officially entered Miyun Reservoir. The water quality of the source water area danjiangkou Reservoir and Miyun Reservoir was mixed. Due to the differences in the water quality and chemical characteristics of the two water sources, the water ecology of Miyun Reservoir was at risk of reconstruction after the exchange. Therefore, it is of great significance to investigate and monitor the water quality and water ecology of the catchment area and the whole reservoir area after the south water is brought into the reservoir, and to clarify the water environment changes of the reservoir, so as to guide the water quality safety management and operation of Miyun Reservoir. Through the analysis of the influence of the inflow of south water on the water quality, phytoplankton and macroaquatic plants of Miyun Reservoir, it can be seen that: at the initial stage of the inflow of south water, all water quality indexes(except pH) of Miyun reservoir have increased;The pH first decreased and then increased, reaching 8.2 at the lowest, and will recover to the level before the south Water storage in 2020. The index values of monitoring eutrophication status in Miyun Reservoir from 2015 to 2020 ranged from 36 to 43, which were all at the moderate level, and the eutrophication status showed a trend of improvement year by year. The probability of the occurrence of bloom in the shallow water area of Kudong and Jingou is higher than that in the deep water area. The number of phytoplankton species in Miyun reservoir changed little, but the composition of dominant algae species changed significantly. After the southern water entered the reservoir, all the submerged plants, emergent plants and terrestrial herbaceous plants were submerged to death. At present, a large number of aquatic plants were found at the entrance of chaohe river and Baihe River, and bristrella and Dendrocalamus were distributed sporadically on the northern bank of the reservoir. It is expected that it will take many years for the aquatic plants to recover from the reservoir.